NEW: disallow in-source builds

CMakeLists.txt

@@ -24,6 +24,9 @@ list(APPEND CMAKE_MODULE_PATH ${CMAKE_SOURCE_DIR}/cmake)
 # Find includes in the build directories
 set(CMAKE_INCLUDE_CURRENT_DIR ON)
 
+# error message when user tries to make in-source build!
+include(jkqtplotter_noInsourceBuilds)
+
 # Common Includes for JKQtPlotter
 include(jkqtplotter_common_include)
 

cmake/jkqtplotter_noInsourceBuilds.cmake

@@ -0,0 +1,11 @@
+if(PROJECT_SOURCE_DIR STREQUAL PROJECT_BINARY_DIR)
+    message(FATAL_ERROR
+        "\n"
+        "In-source builds are not allowed.\n"
+        "Instead, provide a path to build tree like so:\n"
+        "cmake -B <destination>\n"
+        "\n"
+        "To remove files you accidentally created execute:\n"
+        "rm -rf CMakeFiles CMakeCache.txt\n"
+    )
+endif()